Seed placement unit

ABSTRACT

A seed placement unit including a body, a seed channel and a placement chamber, the seed channel extending from a first end, open to the exterior of the body for seed input, to a second end, open to the exterior of the body adjoining the placement chamber, for seed output. A guidance wheel intersects the seed channel and has at least one opening to receive a seed within the seed channel and carry it through the seed channel as the guidance wheel is rotated by a Geneva gear or other suitable mechanism. A closing wheel mechanism in the placement chamber rotates in synchronism with the guidance wheel to receive a seed from the seed channel and transfer the seed to the seed output opening. The seed placement unit may be carried on an agricultural vehicle or other mobile conveyance.

BACKGROUND Field

The invention is related to planters and particularly, although notexclusively, to those for use in automated agriculture systemscomprising one or more driverless vehicles configured to perform theplanting operation without direct intervention or control by anoperator.

Ensuring food supply is the main challenge for the future of human lifeon planet earth. To reach for a sustainable and sufficient food supplycurrent agricultural production systems and methods will need to gothrough radical changes. Arable land is limited: its effective,sustainable use is mandatory, especially as competition for use (Food,Feed, Fuel, Fiber) grows. High production costs provoke high foodprices, especially critical for poor countries, and inaccurate use ofseeds and agrochemicals results in high production costs and wastedresources.

Precision Farming (the accurate use of resources down to the plant assmallest individual unit) is a necessary measure to approach thementioned challenges, but this is hard to achieve with large scaleequipment (from a technical perspective as well as an economicalperspective) and soil damage cannot substantially be reduced on heavyequipment due to the laws of growth (3D mass versus 2D contact area).

Description of Related Art

The answer to some of these issues is small automated driverlessvehicles (robots), also known as autonomous agricultural machines(AAM's) able to operate around the clock without human surveillance. Anexample of such an automated agriculture system is described in thecommonly-assigned International patent application WO2016/087535A1.

The conventional method of planting seeds (named drill seeding) involvesusing a disc, a plow or diverging blades to open a furrow, placing theseeds therein and using a closure device to cover the seeds with soil.This method is widely used in agricultural machine seeding.

OVERVIEW

In accordance with the present invention there is provided a seedplacement unit comprising:

a body;

a seed channel and a placement chamber formed in the body, wherein theseed channel extends from a first end, open to the exterior of the bodyfor the receipt of a seed for placement, to a second end joining theplacement chamber, and the placement chamber has an output open to theexterior of the body;

a guidance wheel and a mechanism connected to impart rotary motion tothe same, the guidance wheel intersecting the seed channel and having atleast one opening to receive a seed within the seed channel and beingarranged to carry the seed through the seed channel as the guidancewheel rotates; and

a seed delivery mechanism in the placement chamber operable to receive aseed from the seed channel and transfer the same to the output open tothe exterior of the body.

Preferably, the seed delivery mechanism comprises a closing wheelrotatably mounted within the placement chamber and having a mechanismconnected to impart rotary motion to the same, and preferably theclosing wheel has at least one opening to receive a seed from the seedchannel and being arranged to carry the seed through the placementchamber to the output open to the exterior of the body.

In an arrangement as set forth in the preceding paragraph, the mechanismcoupled to impart rotary motion to the closing wheel may suitablycomprise a first gear wheel attached to rotate with the guide wheel, anda second gear wheel in driving engagement with the first gear wheel andattached to rotate the closing wheel. Preferably, the gear ratio betweenthe first and second gear wheels is equal to the ratio between thenumber of openings to receive a seed in the guide wheel and the numberof openings to receive a seed in the closing wheel.

Preferably, the mechanism connected to impart rotary motion to theguidance wheel is a Geneva drive having an input rotatable relative tothe body and an output connected to rotate the guidance wheel through apredetermined fraction of a full rotation for each full rotation of theinput. Suitably, the guidance wheel has a plurality of openings toreceive a seed, which plurality is the inverse of the predeterminedfraction of a full rotation imparted by the Geneva drive.

In a seed placement unit according to the invention, a portion of theexterior of the body, adjacent the placement chamber and output, may beshaped to provide a generally wedge-shaped ground engaging portion. Thebody is preferably formed from a sequentially layered stack ofintermediate plates each having a generally identical outer profile andbeing held between respective first and second outer plates, and atleast one of the guidance wheel and closing wheel may then formed from asequentially layered stack of plates in intermeshing engagement with thesequentially layered stack of intermediate plates of the body.Alternately, at least one of the guidance wheel and closing wheel may bepartly formed by bristles in intermeshing engagement with thesequentially layered stack of intermediate plates of the body. In afurther alternative, at least one of the guidance wheel and closingwheel may be a unitary body formed by e.g. casting, molding or 3Dprinting. The generally wedge-shaped ground engaging portion may beformed by sequential variations in outer profile between successiveintermediate plates producing one or more staircase profiles when viewedin cross-section through the stack of plates. Such a wedge-formingstaircase profile may be machined to a continuous sloped or curvingprofile, or may simply be used “as is”, with the omitted machining stepsimplifying construction and reducing tooling costs.

The present invention further provides a seed placement device (orvehicle) comprising a chassis and at least one seed placement unitaccording to the invention mounted thereon.

Preferably, the seed placement device includes a motor and the body isrotatably mounted relative to the chassis and drivingly rotated by themotor, with the mechanism connected to impart rotary motion to theguidance wheel including a fixed connection to the chassis. As will bedescribed with reference to examples below, the seed placement devicemay include a double-ended seed placement unit comprising a pair of seedplacement units according to the invention sharing a common body andmotor coupled to impart rotary motion to the body.

It will be understood that references herein to seed placement includeseed planting, with the differentiation being whether or not the plantervehicle that deposits the seeds at a particular location also closes thesoil over the deposited seed. The seed placement unit of the presentinvention may be provided with additional mechanisms for soil closureover a deposited seed, which additional mechanisms are outside of thescope of the present disclosure. References herein to seeding, planting,or seed placement will be understood to be interchangeable.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will becomeapparent from reading the following description of embodiments of theinvention, given by way of example only, with reference to theaccompanying drawings in which:

FIG. 1 is a perspective view of a self-propelled seeding vehicle;

FIG. 2 schematically represents components of a control system for thevehicle of FIG. 1 ;

FIG. 3 is a perspective view of a seed sorting and planting assembly ofthe vehicle of FIG. 1 ;

FIG. 4 is a perspective view of a seed placement unit of the assembly ofFIG. 3 ;

FIGS. 5A to 5C are a series of sectional schematics through the seedplacement unit of FIG. 4 ;

FIG. 6 is a perspective view of the seed placement unit of FIG. 4 withcomponents omitted;

FIGS. 7A and 7B respectively represent the orientation of the seedplacement unit of FIG. 4 in operational and non-operational modes;

FIGS. 8A to 8C represent the passage of a seed through the seedplacement unit of FIG. 4 as the unit rotates;

FIG. 9 is a sectional side elevation through the assembled seedplacement unit of FIG. 4 ;

FIGS. 10A to 10D are a series of exploded views and FIGS. 10E to 10I area series of sectional views illustrating the assembly of the seedplacement unit; and

FIGS. 11A and 11B represent external shaping formed by the constructionof the body of the seed placement unit.

DETAILED DESCRIPTION

While the disclosure will be described in connection with thesedrawings, there is no intent to limit it to the embodiment orembodiments disclosed herein. For instance, in the description thatfollows, the focus is on a self-propelled agricultural seeding machineembodied as an autonomous agricultural robot, though it should beappreciated that other embodiments of seeding machines are contemplatedto be within the scope of the disclosure. Further, although thedescription identifies or describes specifics of one or moreembodiments, such specifics are not necessarily part of everyembodiment, nor are all various stated advantages necessarily associatedwith a single embodiment or all embodiments. On the contrary, the intentis to cover all alternatives, modifications and equivalents includedwithin the scope of the disclosure as defined by the appended claims.Further, it should be appreciated in the context of the presentdisclosure that the claims are not necessarily limited to the particularembodiments set out in the description.

FIG. 1 shows a vehicle in the form of an autonomous agricultural machine(AAM) 10 intended to be operated in clusters to perform an agriculturaloperation (in this case seeding/planting) on a field without directoperator control. The AAM's are self-propelled and have guidance andself-steering to enable them to traverse a field according to apredetermined path (which may be dynamically reassigned during operationby centralized or remote control) such that a cluster of AAM's cooperateto seed a field with individual seeds planted or deposited atpredetermined locations.

The AAM 10 comprises a base-plate or chassis 12 to which are attachedfour support brackets 14, each mounting a respective drive motor 16,with each motor having an outwardly extending shaft to which areattached respective reduction gear units 20 providing output shafts 18driving wheels 22 (two shown omitted for reasons of clarity). Motivepower for the drive motors 16 is provided by a battery pack 24, withcontrol of the drive to the individual drive motors 16 (includingdifferential steering through control of the motor speed to each wheel)being handled by a drive/control and guidance system—indicated generallyat 26 and described in further detail below with reference to FIG. 2 .

The AAM 10 further comprises a rotating seed sorting and placement unit,indicated generally at 28 and described in further detail below withreference to FIGS. 3 to 10 . The seed sorting and placement unit 28 ismounted on the chassis 12 and operates through an aperture therein todeposit or plant seeds on or in the soil of a field traversed by the AAMunder direction of the drive/control and guidance system 26 controllinga seeder motor 30 of the seed sorting and placement unit 28. Suitablythe seeder motor 30 includes a rotary position sensor (30 a; FIG. 2 )such that the drive/control and guidance system 26 can stop the rotationof a seed placement unit 52 of the seed sorting and placement unit 28with the seed placement unit 52 in one or more predeterminedorientations, as discussed further below, as well as varying the speedof rotation.

The components of the drive/control and guidance system 26 areillustrated schematically in FIG. 2 and are based around a centralprocessing unit (CPU) 32. The CPU 32 may be embodied as a custom-made orcommercially available processor, an auxiliary processor among severalprocessors (although simplicity in component numbers is desirable for anAAM), a semiconductor based microprocessor (in the form of a microchip),a macroprocessor, one or more application specific integrated circuits(ASICs), a plurality of suitably configured digital logic gates, and/orother well-known electrical configurations comprising discrete elementsboth individually and in various combinations to coordinate the overalloperation of the drive/control and guidance system 26.

The CPU 32 is coupled via an address and data bus 34 to an I/O interface36 to an aerial 38 which may provide one or more interfaces to a remotenetwork or control system for a cluster of the AAM's. Additionally(although an additional aerial or antenna array may be used), thisprovides input for positioning data, for example Global PositioningSystem (GPS) or Global Navigation Satellite System (GNSS) data which isresolved in an on-board positioning system 40 to identify the currentlocation of the AAM. With the rotary position sensor 30 a detecting theorientation of the rotating seed placement unit 52 relative to the AAMat the instant of seed placement, the location of individual seeds isalso determined.

Additionally coupled to the CPU 32 via bus 34 are onboard storagedevices represented by read-only (ROM) and random-access (RAM) devices42, 44. The ROM 42 suitably carries the boot-up and general operationalsoftware for the AAM (for example in terms of routines to be followedwhen deviation from a pre-planned path is necessitated by an encounteredobstruction), whilst the RAM 44 captures transitory data such as thelocation of obstacles encountered (location determined byguidance/positioning system 40) and the actual location of seedsplanted/deposited—for example where this departs from a pre-plannedpositioning due to environmental conditions and/or issues with theoperation of the AAM.

When certain embodiments of the drive/control and guidance system 26 areimplemented at least in part as software (including firmware), it shouldbe noted that alternatively or in addition to ROM 42, the software canbe stored on a variety of non-transitory computer-readable medium foruse by, or in connection with, a variety of computer-related systems ormethods. In the context of this document, a computer-readable medium maycomprise an electronic, magnetic, optical, or other physical device orapparatus that may contain or store a computer program (e.g., executablecode or instructions) for use by or in connection with acomputer-related system or method. The software may be embedded in avariety of computer-readable mediums for use by, or in connection with,an instruction execution system, apparatus, or device, such as acomputer-based system, processor-containing system, or other system thatcan fetch the instructions from the instruction execution system,apparatus, or device and execute the instructions.

When certain embodiments of the drive/control and guidance system 26 areimplemented at least in part as hardware, such functionality may beimplemented with any or a combination of the following technologies,which are all well-known in the art: a discrete logic circuit(s) havinglogic gates for implementing logic functions upon data signals, anapplication specific integrated circuit (ASIC) having appropriatecombinational logic gates, a programmable gate array(s) (PGA), a fieldprogrammable gate array (FPGA), etc.

In addition to the above-mentioned capture of AAM positional data, theAAM may be provided with additional sensors to capture furtheroperational machine information (e.g., tilt/yaw variations fromhorizontal, machine performance, battery usage etc.) which may be storedlocally by the CPU 32 in memory 44 and made available by transmissionvia aerial 38 (if the device is configured also to transmit), ortransferred via memory device, such as a memory stick, plugged into theAAM by the operator, or stored remotely and accessed, such as from adata structure (e.g., database) upon operator request or automaticallyupon detection of an event (e.g. conditions indicating failure of anindividual AAM of a cluster).

Output from the CPU 32 provides a controlled drive signal to the fourindividual wheel drive motors 16, or such other drivetrain mechanism asthe AAM may have (e.g. independently controllable tracks instead ofwheels) as well as to the seeder motor 30 of the seed placement unit 28,as will be described in further detail below. It is important to notethat the operation of the seed sorting and placement unit 28 is notmechanically linked to the drive motors 16 of the AAM, and accordinglythe operation to place/plant a seed occurs purely on the basis of theinstantaneous AAM (vehicle) location and the current position of theseed placement unit 28 as determined by rotary position sensor 30 a ofseeder motor 30 without reference to the degree of turn of the wheels(which may otherwise give wrong results in slippery conditions).

FIG. 3 shows the main components of the seed sorting and placement unit28, which is mounted to the chassis 12 of the AAM 10 by a pair ofmounting brackets 46. Above the chassis, a mounting bracket 48 supportsthe drive seeder motor 30 which controllably rotates a sorting/singlingunit 55 through a reduction gear 31 and the seed placement unit 52(described below) via pair of pulleys 33 and belt 50 arrangement. Thisdriveline may alternatively include the above-mentioned rotary positionsensor 30 a at another position.

A seed tank or reservoir 54 receives seeds to be planted or placed. Aswill be understood in the context of an AAM, replenishing the reservoirmay be an autonomous activity triggered when the reservoir is low/empty,with the AAM leaving its current planned planting path to e.g. go to ahost vehicle at the side of the field from which the reservoir may bereplenished, before returning to the planned task.

Adjacent the reservoir 54, and coupled to receive seeds therefrom, isthe sorting/singling unit 55 which takes seeds from the reservoir 54and, in known fashion, separates them and outputs them as a sequence ofindividual seeds in a downward channel to transfer unit 56, withindividual seeds feeding into one of a pair of seed channels (describedbelow) in the seed placement unit 52, when the seed placement unit 52 isat a particular predetermined point in its rotation.

The rotating seed placement unit 52 is shown in greater detail in theperspective views of FIGS. 4 and 6 and the schematic sectional views ofFIG. 5A to 5C. Whilst the present invention encompasses a single-endedmechanism, a double-ended version (as shown) is preferred, with two suchmechanisms mounted end to end and rotating about a common axis. The seedplacement unit 52 is formed as a layered assembly of components, withthe sequence of FIGS. 5A to 5C representing a double-ended version withsuccessive layers of components omitted. In FIG. 6 , some furthercomponents are omitted, from the upper mechanism only, for clarity.

In a first embodiment, considering just the components of a single-endedmechanism, the seed placement unit 52 comprises a body or housing 60rotatable by motor 30 about a central and generally horizontal axis 61.The housing consists of a structure, provided by stacked sheet metalparts, which structure is described below in detail. The rotating seedplacement unit 52 uses the concept of a Maltese gear or Geneva drive formain drive, the main components will now be explained.

The main body 60 is rotated about axis 61 by motor 30 (FIG. 3 ). TheMaltese gear contains a drive wheel 70 which is shown in position inFIG. 5A and omitted, but represented by dotted lines, in FIG. 5B. Thedrive wheel 70 has a pin 71 attached and is fixed relative to themounting brackets 46 (so that it does not rotate with body 60). Withinthe body 60, and rotatably mounted relative to body 60, there is afurther component of the Maltese gear, namely the Maltese cross part 75.The Maltese cross part 75 is a plate provided with four slots 76extending radially inwards towards the center of the plate forengagement with the pin 71.

During rotation of the body 60, the pin 71 engages slots 76 so that theMaltese cross part 75 is rotated relative to body 60. As the Maltesecross part 75 is provided with four slots 76, a full 360° turn of body60 results in a 90° turn of the Maltese cross part 75 relative to body60.

With reference to FIGS. 5B and 5C, the Maltese cross part 75 is fixedlyconnected to a first gear wheel 80 for joint rotation therewith about anaxis through the center of the cross part 75. A second rotatably mountedgear wheel 81, located generally outwards of the first gear wheel 80relative to the center axis 61, engages with first gear wheel 80. As thenumber of teeth provided for first gear wheel 80 is twice that of thesecond gear wheel 81, the second gear wheel 81 provides a full turn(relative to body 60) if the first gear wheel 80 does a half turn.

To summarize the rotational movement of the main components:

-   -   During a full 360° turn of the body 60, the Maltese cross part        75 is pivoted through 90° by the engagement of the pin 71 with        one of the slots 76.    -   The first gear wheel 80 is moving with Maltese cross part 75 so        that, with a 360° turn of the body 60, first gear wheel 80 is        also incrementally moved through 90° anti-clockwise relative to        body 60.    -   Due to the gearing ratio between the first and second gear        wheels 80, 81, with a 360° turn of the body 60, second gear        wheel 81 turns 180° clockwise relative to body 60.

The seed placement will now be described, whereby the driving directionDD of the AAM is to the left (shown with arrow DD in the figures) andthe rotation of the seed placement unit 52 is anti-clockwise, as shownwith arrow R.

The first gear wheel 80 is fixed to a rotatably mounted guidance wheel90 which, as shown in FIG. 5C, provides four seed chambers 91 a-91 d.During operation, three of these seed chambers have a seed carriedinside while the fourth one is empty. Note that in the orientation ofthe Figures, guidance wheel 90 is pivoting anti-clockwise in FIG. 5A to5C and FIG. 6 .

The second gear wheel 81 is fixed to a rotatably mounted closing wheel100 which provides two radially opposed seed chambers 101 a, 101 b inits periphery. During operation, one seed chamber is storing a seedwhile the other is discharging the seed to the ground. Closing wheel 100is pivoting anti-clockwise in FIG. 5A to 5C and FIG. 6 .

As shown in FIG. 6 , guidance wheel 90 consists of several sheet metalparts stacked together to form a pectinated cross section which is incooperation with a seed channel 110 formed in body 60 by the stackedsheet metal parts forming the body as described below. Closing wheel 100consists of several sheet metal parts stacked together to form apectinated cross section which is in cooperation with a placementchamber 120 formed in body 60 by the stacked sheet metal parts formingthe body as shown in FIG. 10E and as described below.

As mentioned above, the arrangement of seeding placement unit 52 isoptimized as a back to back (or end to end) arrangement of two plantersas described above. Reference to FIGS. 5A to 5C and FIG. 6 will show howthis is achieved with the addition of a further Maltese cross part 75,first gear wheel 80, second gear wheel 81, guidance wheel 90, closingwheel 100 and the respective provisions in body 60 such that both unitsutilize the single pin 71 and operate 180 degrees out of sequence as theunit rotates to transport a seed also along second seed channel 111 andplacement chamber 121.

A further benefit of the double-ended arrangement (as illustrated byFIGS. 5A to 5C), coupled with the control system 26 operating theplanter mechanism independently of the motion (speed and/or position) ofthe AAM across the ground is that when the AAM is in a non-operationalstate, necessitating crossing the field to restock with seeds to thereservoir 54, the seed placement unit 52 may be turned to a generallyhorizontal orientation (with the two closing wheels 100 generallyhorizontally aligned) such that the reduced width of unit 52 compared tothe ends from which the seeds emerge) gives an improved ground clearanceG2 compared to that G1 (between body 60 and ground) when working and adistal end of the body 60 (containing one of the closing wheels 100) isclosest to, or engaging, ground, as shown in ground by opening a recessto receive a seed. As the direction of driving (indicated with arrow DD)and the direction of rotation R of the seed placement unit 52 act in thesame direction (on the level of ground), and as the speed over ground ofthe vehicle and the seed placement unit 52 is similar on ground level,the vehicle is not accelerated or braked by rotation of the seedplacement unit 52. This enables an energy saving operation.

Turning now to the operating sequence illustrated by FIG. 8 , the body60 is shown in a sequence of positions 1 to 8 as it turns through 360°with the relative position of ground shown by horizontal line G. As bestseen in FIG. 8A, the guidance wheel 90 and closing wheel 100 are onlypivoted when the body 60 turns within a range R1 of 90° betweenpositions 5 and 8 (from an angle of around 15° below horizontal toaround 15° past vertical position indicated at α) when the seed isplaced in ground at position 8. During the rest of the rotation (270°),guidance wheel 90 and closing wheel 100 are kept in their respectivepositions relative to body 60 by friction or spring bias.

FIG. 8B shows a detail of FIG. 8A reduced to the travel betweenpositions 4 and 8 (including range R1 between positions 5 and 8) andshowing the relative positions of four sequentially received seedsS.1-S.4 forwarded in one of the planters of the seeding unit. Inposition 4, the first received seed S.1 is held in a recess of theclosing wheel 100 in placement chamber, whilst three further seedsS.2-S.4 are held in respective recesses of the guidance wheel 90 (withseed S.4 having been received between positions 3 and 4). At position 5,the generally wedge-shaped part 700 of the body 60 in the vicinity ofthe outlet 125 (described further below) has begun to engage the groundG, and the Geneva drive begins to index the guidance wheel through aquarter turn, and the closing wheel through a half turn. Throughpositions 6 and 7, the wedge-shaped part 700 creates an opening and theclosing wheel rotates to enable the seed S.1 to pass through opening125, whilst at the same time the closing wheel 100 is receiving the nextseed S.2. Further rotation leads to precise positioning of the firstseed S.1 by closing wheel 100 in the created opening at position 8.

FIG. 8C illustrates the way which a seed passes through the body 60 asit is rotated through four full turns. Note that guidance wheel 90 andclosing wheel 100 are shown in a static position in dotted lines. Thesequence is as follows:

-   -   1. During the first turn, a seed 130 enters from        sorting/singling unit 55 into the seed channel 110 and is moved        by the 90 degree rotation of guidance wheel 90 to a position        indicated at 130 a.    -   2. During the second turn, the seed 130 is moved in the seed        channel 110 by a further 90 degree rotation of guidance wheel 90        to a position indicated at 130 b.    -   3. During the third turn, the seed 130 is moved in the seed        channel 110 by a further 90 degree rotation of guidance wheel 90        and transferred from the seed channel 110 to a placement chamber        120 containing the closing wheel 100, as indicated at position        130 c.    -   4. During the fourth turn, the seed 130 is carried by closing        wheel 100 through the placement chamber 120 to an opening 125 in        the body 60, and is pushed into soil by the closing wheel 100 at        position 130 d.

Subsequent seeds are transported in like manner.

For each full turn of body 60, one seed is transferred from thesorting/singling unit 55 into each planter of the seed placement unit 52and released into ground, such that the seed placement unit 52 can placetwo seeds per full turn.

It is envisaged that, depending on the number of slots in the Maltesecross part 76, the concomitant ratio between first gear wheel 80 andsecond gear wheel 81 and the number of seed chambers 91, 101 in guidancewheel 90 and closing wheel 100, different seeding rates (seeds per fullturn) can be provided.

The stacked structure 600 of body or housing 60, and its provision ofwedge-shaped ground-engaging portion 700, is now explained withreference to FIGS. 9 to 11 .

FIG. 9 shows a sectional view taken on line A-A of FIG. 5B showing thebody 60 and the structure 600. The structure 600 generally consists ofthree sections/levels 610, 620, 630 each comprised of a number ofintermediate plates sandwiched between outer or bounding plates, inbetween final outer plates 680 and 690 at each end.

The first section 610 contains the components of the Maltese gear withdrive wheel 70 and pin 71 (shown in FIGS. 5A, 5B) which engages withMaltese cross part 75. Distance plates 611, 612 and plate 613 areprovided and enlarge the space for installation (as shown more clearlyin the exploded views of FIGS. 10A and 10B).

The second section 620 contains first gear wheel 80 and second gearwheel 81 mounted in driving connection. In the orientation of FIG. 9 ,second section 620 is enclosed on the left side by plate 621 andconcludes at the right hand side with plate 622. First gear wheel 80 andsecond gear wheel 81 are also enclosed at their radial edges by plate622 (as shown in the exploded view of FIG. 10B).

The third section 630 contains guidance wheel 90 and closing wheel 100.In this section, the seeds are transported through the body 60. Section630 is enclosed on the right side by plate 638. As can be seen in FIG.10C, section 630 is assembled from two shapes of plate 631-637 which arealternately stacked. The first shape of plate 631, 633, 635, 637 hasgenerally circular cutouts 631 a, 633 a, 635 a, 637 a forming an innercontour sized to accommodate the guidance wheel 90 and closing wheel 100of each planter assembly. The second shape of plate 632, 634, 636 has apair of more irregularly shaped cutouts 632 a, 634 a, 636 a forming aninner contour defining the seed channel 110 and placement chamber 120.

As the guidance wheel 90 and closing wheel 100 are assembled frommultiple discs 90 a/100 a with spacers 90 b/100 b in between (not shownin FIG. 9 ), a basset or comb-shaped profile (seen in a section throughthe axis of rotation) is formed, as shown in FIGS. 10E and 10F. Asschematically depicted in FIG. 10E, in a first area A1 the innercontours 631 a-637 a form the counterpart to this basset shape of wheels90, 100 so that the alternate plates 632, 634, 636, enclosing plates638, 640 and guidance wheel 90 or closing wheel 100 are in intermeshedrelationship and able to move relative to each other. As depicted InFIG. 10F, in second area A2 the inner contours 631 a-637 a (enclosed byplates 638, 640) form seed channel 110 and placement chamber 120 inwhich guidance wheel 90 or closing wheel 100 can move the seed S takenby rotation of guidance wheel 90 or closing wheel 100. Whenpre-assembled, neither guidance wheel 90 nor closing wheel 100 can beplugged through a complete plate 632 having inner contours 632 a, and sothe plates 631-637 are separate to enable assembly.

In the embodiments described above, body 60, guidance wheel 90 andclosing wheel 100 are made of stacked sheet metal parts. Alternatively,molded parts, castings or 3D printed parts may be used instead or incombination. For example, guidance wheel 90 and closing wheel 100 maycontain discs 90 a/100 a made of rubber stacked with plastic spacers 90b/100 b. This may enable a more gentle seed transport.

A further alternative embodiment (with regard to FIG. 10E) is shown inFIG. 10G wherein the guidance wheel 90 and/or closing wheel 100 consistsof a wheel body 90 c/100 c and fibrous resilient bristles 90 d/100 d(flexible enough to move if in contact with the body, but stable enoughto take the seed safely). The bristles 90 d/100 d may be attached to thewheel body 90 c/100 c by bonding or by in-mold forming (whereby bristles90 d/100 d are inserted into the tool before molding body 90 c/100 c).Similar to FIG. 10E, in a first area A1 the inner contours 631 a-637 aform the counterpart to this basset shape of bristles 90 d/100 d so thatthe alternate plates 632, 634, 636, enclosing plates 638, 640 andguidance wheel 90 or closing wheel 100 are in intermeshed relationshipand able to move relative to each other. Further similar to FIG. 10F,but not shown in detail, in a second area the inner contours 631 a-637 a(enclosed by plates 638, 640) form seed channel 110 and placementchamber 120 in which bristles 90 d/100 d of guidance wheel 90 or closingwheel 100 can move the seed taken by rotation of guidance wheel 90 orclosing wheel 100. FIG. 10H shows, for guidance wheel 90 only (althoughclosing wheel 100 may be similarly constructed), that four bristles 90 dare arranged at the circumference of wheel body 90 c at an offset angleof 90° and in radial direction so that, similar to guidance wheel 90shown in FIG. 5C (schematically depicted herein with line L1), four seedchambers 91 a-91 d are provided to carry the seed inside seed channel110. The bristles 90 d may thereby extend with an angle to radialdirection to ensure that the seed is moved radially outwards. Thisembodiment has the advantage that the (small) flexibility of bristles 90d provides a smoother seed guidance and allows for tolerances in thecomb-shaped profile.

In a further embodiment shown with FIG. 10I, the body 60 may comprise areduced number of plates 631, 633, 635, whereby plate 631 (merged withplate 632 shown in FIGS. 10E to 10G) provides both contours 631 a, 632a, plate 633 (merged with plate 634 shown in FIGS. 10E to 10G) providesboth contours 633 a, 634 a and plate 635 (merged with plates 636 and 637shown in FIGS. 10E to 10G) provides the contours 635 a, 636 a and 637 a.Instead of using sheet metal plates as shown in FIGS. 10E to 10G, plates631, 633, 635 may then be produced by molding, casting or machining toenable the non-flat design with local indentations. This reduces partscosts and assembly time at the expense of tooling costs compared to thestacked plate arrangement.

In a further embodiment, the guidance wheel 90 and/or closing wheel 100may consist of multiple wheel body parts 90 e/100 e, 90 f/100 f stackedtogether, each having attached bristles 90 d/100 d. If each of plates631, 633, 635 may be a single part extending over complete circumferenceof body 60, neither guidance wheel 90 nor closing wheel 100 can beplugged through a complete plate 631 having inner contours 632 a, buthaving multiple and detachable wheel bodies 90 e/100 e, 90 f/100 fenables a synchronous stacking of plates 631, 633, 635. The order ofassembly is generally in the left-to right direction with reference toFIG. 10I and may have the following steps:

-   -   1. The stacking assembly starts with enclosing plate 640 resting        on a horizontal base.    -   2. First wheel body 90 e/100 e (on left side in FIG. 10I) is        assembled.    -   3. Plate 631 is then stacked with the contour 631 a encompassing        the bristles 90 d/100 d of the previously mounted first wheel        body 90 e/100 e.

4. Second wheel body 90 f/100 f is assembled next.

5. Plate 633 is then stacked with the contour 633 a encompassing thebristles 90 d/100 d of the previously mounted second wheel body 90 e/100e.

6. Third wheel body 90 f/100 f is assembled next.

7. Plate 635 is then stacked with the contour 635 a encompassing thebristles 90 d/100 d of the previously mounted second wheel body 90 f/100f.

8. Fourth wheel body 90 e/100 e is assembled next (in oppositeorientation compared to First wheel body 90 e/100 e in step 2) into thecontour 637 a in the previously mounted plate 635.

9. The stacking assembly for section 630 is then finished with enclosingplate 638 mounted on top of the stack.

It is envisaged that the stacking assembly requires the stacked parts tobe impeded against loosening or relative rotation (especially theassembly guidance wheel 90 or closing wheel 100) and furthermorerequires means to enable correct positioning during assembly. This maybe provided in known manner by screws, pins or matching contours e.g.when molded parts are used.

FIG. 10D shows an overall exploded view of the three sections 610, 620,630. As can be seen (also in FIG. 9 ), between sections 620 and 630 aseparating plate 640 is provided to separate the chambers of the twosections which is necessary to enable lubrication to be applied to thecomponents of sections 610 and 620 without lubricant contaminationimpacting seeds in section 630.

Although shown in FIG. 10 as two sets of similar plate designs, theremay be variations between plates of generally the same design to providefurther advantage of the structure 600 as shown in FIGS. 4 to 6 and 11 .At the edge where the rotating body 60 engages the ground to generate anopening or trench to receive a seed, a wedge 700 is formed by the plates631-637 having a varying outer contour at this edge, which wedgeimproves the cutting action and reduces the energy required to generatethe opening. The construction technique producing the body 60 enablesthe building of a wedge just from a staircase profile of stacked plates,as shown in FIG. 11A, rather than requiring expensive, three dimensionalmachining of a body outer shell. However, this staircase profile may bemachined to a continuous slope or curved profile as illustratedrespectively at 700A and 700B in FIG. 11B.

In the foregoing the applicants have described a seed placement unitthat comprises a body 60 in which there is formed a seed channel 110 anda placement chamber 120, with the seed channel extending from a firstend, open to the exterior of the body for the receipt of a seed 130 forplacement, to a second end joining the placement chamber 120, and theplacement chamber 120 has a seed output 125 open to the exterior of thebody 60. A guidance wheel 90 intersects the seed channel 110 and has atleast one opening 91 to receive a seed 130 within the seed channel andcarry it through the seed channel as the guidance wheel 90 is rotated bya Geneva gear or other suitable mechanism. A closing wheel mechanism 100in the placement chamber 120 rotates in synchronism with the guidancewheel 90 to receive a seed 130 from the seed channel 110 and transferthe same to the seed output 125. A seed placement device or vehicle 10carrying the placement unit is also provided.

From reading the present disclosure, other modifications will beapparent to persons skilled in the art. Such modifications may involveother features which are already known in the field of agriculturalmachines and component parts thereof and which may be used instead of orin addition to features already described herein, and the scope of theinvention is limited only by the following claims.

The invention claimed is:
 1. A seed placement unit comprising: a body; aseed channel and a placement chamber formed in the body, wherein theseed channel extends from a first end, open to an exterior of the body,to a second end joining the placement chamber, and the placement chamberhas an output open to the exterior of the body; a guidance wheel coupledto a rotary motion mechanism, the guidance wheel intersecting the seedchannel and having at least one opening to receive seed within the seedchannel and configured to carry seed through the seed channel as theguidance wheel rotates; and a seed delivery mechanism in the placementchamber operable to receive seed from the seed channel and transfer thesame to the output open to the exterior of the body, wherein the rotarymotion mechanism connected to the guidance wheel is a Geneva drivehaving an input rotatable relative to the body and an output connectedto rotate the guidance wheel through a predetermined fraction of a fullrotation for each full rotation of the input.
 2. The seed placement unitas claimed in claim 1, wherein the seed delivery mechanism comprises aclosing wheel rotatably mounted within the placement chamber and coupledto the rotary motion mechanism.
 3. The seed placement unit as claimed inclaim 2, wherein the closing wheel has at least one opening to receiveseed from the seed channel and configured to carry seed through theplacement chamber to the output.
 4. The seed placement unit as claimedin claim 2, wherein the rotary motion mechanism coupled to the closingwheel comprises a first gear wheel attached to rotate with the guidancewheel, and a second gear wheel in driving engagement with the first gearwheel and attached to rotate the closing wheel.
 5. The seed placementunit as claimed in claim 4, wherein the gear ratio between the first andthe second gear wheels is equal to the ratio between a number ofopenings of the at least one opening in the guidance wheel and thenumber of at least one opening in the closing wheel.
 6. The seedplacement unit as claimed in claim 1, wherein the at least one openingof the guidance wheel to receive seed is a plurality of openings, thenumber of which plurality is the inverse of the predetermined fractionof a full rotation imparted by the Geneva drive.
 7. The seed placementunit as claimed in claim 1, wherein a portion of the exterior of thebody, adjacent the placement chamber and the output, is a wedge-shapedground engaging portion.
 8. A seed placement unit comprising: a bodyformed from a sequentially layered stack of intermediate plates, eachintermediate plate having a generally identical outer profile and heldbetween respective first and second outer plates; a seed channel and aplacement chamber formed in the body, wherein the seed channel extendsfrom a first end, open to an exterior of the body, to a second endjoining the placement chamber, and the placement chamber has an outputopen to the exterior of the body; a guidance wheel coupled to a rotarymotion mechanism, the guidance wheel intersecting the seed channel andhaving at least one opening to receive seed within the seed channel andconfigured to carry seed through the seed channel as the guidance wheelrotates; and a seed delivery mechanism in the placement chamber operableto receive seed from the seed channel and transfer the same to theoutput open to the exterior of the body.
 9. The seed placement unit asclaimed in claim 8, wherein the guidance wheel is formed from asequentially layered stack of plates in intermeshing engagement with thesequentially layered stack of intermediate plates of the body.
 10. Theseed placement unit as claimed in claim 8, wherein the guidance wheel ispartly formed by bristles in intermeshing engagement with thesequentially layered stack of intermediate plates of the body.
 11. Theseed placement unit as claimed in claim 8, wherein the guidance wheel isa unitary body.
 12. A seed placement vehicle comprising: a chassis; anda seed placement unit mounted on the chassis, the seed placement unitincluding— a body; a seed channel and a placement chamber formed in by afixed, continuous recessed portion in a structure of the body, whereinthe seed channel extends from a first end, open to an exterior of thebody, to a second end joining the placement chamber, and the placementchamber has an output open to the exterior of the body; a guidance wheelcoupled to a rotary motion mechanism, the guidance wheel intersectingthe seed channel and having at least one opening to receive seed withinthe seed channel and configured to carry seed through the seed channelas the guidance wheel rotates; a seed delivery mechanism in theplacement chamber operable to receive seed from the seed channel andtransfer the same to the output open to the exterior of the body; and amotor, wherein the body is rotatably mounted relative to the chassis anddrivingly rotated by the motor' and the rotary motion mechanismconnected to the guidance wheel has a fixed connection to the chassis.